Novel approaches for environmental bioreporting of the presence of toxic wastes and environmental pollution are sorely needed. The explosion of knowledge in molecular biology, genetics, and biotechnology provides an unparalleled opportunity to develop new environmental bioreporting techniques. In this proposal, population genetic approaches, using RAPD- PCR technologies, will be developed to investigate the genetic structure of selected aquatic arthropod bioreporter species in the Arkansas River - California Gulch Superfund Site, where the water quality is extremely poor due to heavy metal contamination from past mining and metallurgical operations. This approach will permit identification of impediments to gene flow in the bioreporter species, which may be directly attributable to environmental pollution. Molecular genetic approaches, including differential display - PCR, will be used to identify specific metal responsive genes (biomarkers) which determine tolerance to heavy metals in the bioreporter species. Metal responsive genes will be cloned, regulatory sequences identified, characterized, and this information used to develop molecular genetic biomarkers of heavy metal pollution. These two approaches, population genetic and molecular genetic, will provide environmental bioreporting capability at the population and individual level. Since the selected bioreporter species spend their life cycles and indeed generations in the sites to be studies, analysis of the naturally exposed populations of bioreporters may provide a current as well as historical record of environmental contamination. These modern molecular approaches for environmental bioreporting will be widely applicable to assess heavy metal pollution at alternate sites and to assess bioreporter species genetic responses to alternate types of pollution.